<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
    <script>
        function f1(o){
            console.log(o);
            o.style.width="200px";
            o.style.height="300px";
            o.style.background="yellow";
        }
    </script>
</head>
<body>
    <!--this表示的是事件源：触发事件的元素-->
    <div onclick="f1(this)">div</div>
</body>
</html>